Liuwei Dihuangwan Regulate Brain Microvessels in SAMP8 Mice Through RAGE/LRP1 Receptors / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo investigate the protective effect of Liuwei Dihuangwan on neurovascular injury in SAMP8 mice. MethodThe Alzheimer's disease （AD） model with insufficiency of kidney essence was induced in 75 SAMP8 mice aging 6 months. The model mice were divided into model group， positive control group （donepezil hydrochloride， 0.747 mg·kg-1·d-1）， and high-， medium-， and low-dose Liuwei Dihuangwan groups （2.700， 1.350， 0.675 g·kg-1·d-1）， with 15 mice in each group. Fifteen SAMR1 mice were assigned to a normal control group. All mice were administered continuously for 2 months. The spatial memory of mice was tested by the Morris water maze. Hematoxylin-eosin （HE） staining was used to observe the pathological changes in the hippocampus and cortex of brain tissues. The immunohistochemical method （IHC） was used to detect the deposition of amyloid β-protein （Aβ） and the expression of von Willebrand factor （vWF） and CD34 in the hippocampus and cortex of brain tissues. Electron microscopy was used to observe the ultrastructural changes in cerebral microvessels. Western blot was used to detect the protein expression levels of the receptor of advanced glycation endproduct （RAGE）， low-density lipoprotein receptor-related protein 1 （LRP1）， vascular endothelial growth factor A （VEGF-A）， and P-selection in the hippocampus and cortex of brain tissues. ResultCompared with the normal control group， the model group showed prolonged escape latency and swimming distance （P<0.01）， increased number of glial cells， decreased number of nerve cells， blurred tight junctions or enlarged gap of the brain microvascular endothelial cells， severely injured membrane structure， swollen mitochondria of endothelial cells， ruptured membrane， massive dissolution in cristae， increased protein expression of Aβ and vWF in the hippocampus and cortex （P<0.01）， reduced protein expression of CD34 （P<0.05）， elevated protein expression of RAGE and P-selection in the cortex （P<0.01）， and decreased protein expression level of LRP1 and VEGF-A （P<0.01）. Compared with the model group， the Liuwei Dihuangwan groups showed shortened escape latency and swimming distance （P<0.05）， reduced number of glial cells in the cortex and hippocampus， increased number of microvessels in the cortex， clear double-layer membrane structure in tight junctions between the microvascular endothelial cells， increased number of mitochondria with intact membrane and recovered mitochondrial cristae， decreased protein expression of Aβ， vWF， RAGE， and P-selection in the hippocampus and cortex （P<0.05）， and increased protein expression of CD34， LRP1， and VEGF-A （P<0.05）. ConclusionLiuwei Dihuangwan can regulate Aβ metabolism through the RAGE/LRP1 receptor system and promote cerebral microvascular angiogenesis by inhibiting vWF expression and increasing VEGF-A and CD34， thereby improving cerebral microvascular injury in SAMP8 mice.